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160 or 180 degree thermostat??

T

tcm glx

NAXJA Member #1033
Location
Riverside California
I have heard alot of conversation about how running a lower degree thermostat will cause porr gas mileage. Is this true, and if so by how much....is running a 180 degree thermo doable without killing the mileage, what about a 160 degree thermo?
any input would be appreciated.
 
i ran a 160 degree t stat for a while, and it sucked! it killed my gas milage and hurt performance, and not to mention my jeep never warmed up in the winter, so i went back to a stock 195 degree t-stat.
 
Ipkyss327 said:
What would you reason for running a 160 be? The motor is made to run between 200-210 i believe. And comes with a 194 in it.
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That is why the gas mileage drops. the engine is made to run at the higher range. putting in a 160 degree thermo, causes the computer to think the engine is not warming up properly, thus causeing the engine to run rich, ie using more fuel.
 
If you like heat in the winter don't go lower than 180. I have a 180 and it runs nice and cool in the summer but the heat is definatly not as warm as it was with 195.
 
if your having problems overheating a lower thermostat is not the answer replace the one ya have with another stock one and run thru the rest of the cooling system till ya find the prob. the prob is the engine dosn't change to it's closed loop operation untill the engine reaches operating temp 190-210ish (i beleive) anythign below that temp and the engine runs of a few preset parameters which are not the most fuel efficient. after the engine warms up it begins taking readings from vairious sensors to adjust the a/f ratio to an optimum setting. so in a nut shell you not going to get any advantages out of a chilly t-stat stick with stock in this case.
 
jeepguy97 said:
If you like heat in the winter don't go lower than 180. I have a 180 and it runs nice and cool in the summer but the heat is definatly not as warm as it was with 195.
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X2...
 
bj-666 said:
if your having problems overheating a lower thermostat is not the answer replace the one ya have with another stock one and run thru the rest of the cooling system till ya find the prob. the prob is the engine dosn't change to it's closed loop operation untill the engine reaches operating temp 190-210ish (i beleive) anythign below that temp and the engine runs of a few preset parameters which are not the most fuel efficient. after the engine warms up it begins taking readings from vairious sensors to adjust the a/f ratio to an optimum setting. so in a nut shell you not going to get any advantages out of a chilly t-stat stick with stock in this case.
Click to expand...
In thery it should set a trouble code, and light the check engine light if it never reaches proper oprerating temp, or closed loop operation within a set amount of time.
 
Please use a stock 195*F temperature one ( part number 4365 on the Mr. Gasket version ) so as your computer wont think it is still in the warm up cycle and stay in open loop meaning the O2 sensor is not read and you run rich. Also, the higher the temp you can get the more efficient your engine is. Engineers are running the temperatures higher as materials and designs improve. For every 10F under 180F your engine wear rate doubles due to chemical reactions on the surface of the cylinder walls. Running a 160F thermostat QUADRUPLES your engine wear rate. For every mile you drive your engine wears like it has been driven four miles. The chemical reactions drop little abrasive oxide particles in the oil that eats up the bearings and everything else as well.
 
Gojeep said:
Please use a stock 195*F temperature one ( part number 4365 on the Mr. Gasket version ) so as your computer wont think it is still in the warm up cycle and stay in open loop meaning the O2 sensor is not read and you run rich. Also, the higher the temp you can get the more efficient your engine is. Engineers are running the temperatures higher as materials and designs improve. For every 10F under 180F your engine wear rate doubles due to chemical reactions on the surface of the cylinder walls. Running a 160F thermostat QUADRUPLES your engine wear rate. For every mile you drive your engine wears like it has been driven four miles. The chemical reactions drop little abrasive oxide particles in the oil that eats up the bearings and everything else as well.
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Not to discredit you, but I would think the cylinder walls would be greater than 180* even with a 160* thermostat. Also what about all the hours that a motor sits at non running temps, and the fact most all manufactures say warming up (idling) a engine for more than two minutes is just wasting gas, and has no effect on the wear of it. ? Can you explain this a bit better as I am curious?
 
Last edited:
GoJeep has hit several very good points...not only has he hit them..but he is correct.

Scooby asks a valid question...won't the cylinders run warmer than 180 anyway? The answer is yes...sort of. The question of coolant temperature indirectly relates to cylinder temperature. But the issue from the engineering point is to have correct clearance for the piston and the piston rings.

If the cylinders do not warm properly, the piston never expands to it's intended shape...it may rock in the bore...which accellerates wear..The rings never expand fully...the result is blowdown into the crankcase. The combustion byproducts that get past contaminate the oil..the contaminants are spread throughout the engine...resulting in acid, moisture and particulate contamination.

Lastly, an engine is driven by heat...the less heat that goes out of the cooling system, the more is available for it's intended purpose....provide cylinder pressure...that is one if the reasons a warmer engine can be more efficient.
 
scoobyxj said:
Not to discredit you, but I would think the cylinder walls would be greater than 180* even with a 160* thermostat. Also what about all the hours that a motor sits at non running temps, and the fact most all manufactures say warming up (idling) a engine for more than two minutes is just wasting gas, and has no effect on the wear of it. ? Can you explain this a bit better as I am curious?
Click to expand...

Idling an engine really helps it more than hurts it. Look at it this way...why can rigs go 100s of thousands of mils before rebuilds? Because they are rarely shut off. Start up is the hardest on a engine because nothing is lubricated. Besides wasting gas idling has only positive side effects.
 
Has now been answered anyway and they are not my facts that were quoted but from research I did and gained from people with a lot more knowledge than me in that field. :)
 
The other problem with a colder engine is that the oil may not burn off the water. Oil collects some water when it cools down. Running a lower temp thermostat or none at all can be done during the summer months or in the deep south. Still, I wouldn't do it myself. I did see an oil pan from a SBC in Tulsa that was just about filled with oil that was gelled. It was at an Auto Parts store. THe guy said the whole engine was that way. I would figure that he wasn't getting his oil heated up. If your having temp problems, try and hi-po water pump, Modine or CFS radiator and possible a HESCO thermostat housing. After your engine heats up past what ever temp you thermostat is rated at, it isn't going to help keep your engine any cooler or not much.
Tom
 
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